The present application relates to plumbing fittings and fixtures and water supply systems and installations for washing, showering, bathing and the like that employ such plumbing fittings and fixtures. The concepts disclosed herein have particular, but not exclusive, application to mixer valves (alternatively referred to as “mixing valves”), especially thermostatic mixer valves. More particularly, the present application relates to an arrangement for thermally disinfecting mixer valves.
Mixer valves that dispense blended fluids such as water (e.g., hot and cold supplies, mixing to a typical washing/showering temperature of around 40° C.) may be prone to harboring micro-organisms. Such micro-organisms can enter the valves either through the supply water or through splash back into the spout outlet. This problem is particularly problematic since micro-organisms are particularly prone to proliferation within a temperature range of 35 to 45° C. The presence of micro-organisms in waterways used for washing/showering can give rise to health risks where such micro-organisms may be contained in water discharged from the mixer valve. For example, when washing/showering, micro-organisms present in the water may enter the body through cuts and abrasions in the skin or may be inhaled.
These problems can be exacerbated by other factors, including the use in valve components of certain polymers or elastomers that provide a suitable habitat for sustaining micro-organisms in a living state and/or that encourage micro-organism growth and development, the existence of stagnant areas within the valve where water can be trapped in low circulation areas, high volumes of residual water contained within the valve once shut off, and large wetted areas within the valve, among others.
It is known to employ a thermal disinfection routine in which hot water is used to kill/remove micro-organisms in waterways used for washing/showering. Such disinfection routines involve flushing the waterways with water at an elevated temperature, typically at least 60° C., for a time sufficient to kill or remove micro-organisms from the valve.
The use of such hot water disinfecting/cleaning routines in waterways used for washing/showering can give rise to other issues, however. For example, in the event that a user comes into contact with the hot water being discharged, the user may suffer scalding of the exposed skin or physical discomfort from the high temperature water. Another issue relates to the cost and other difficulties associated with providing and maintaining high (above 60° C.) hot water temperatures for a sustained period of time sufficient to perform the cleaning routine. Such hot water may also undesirably generate excessive amounts of steam in the surrounding area, and the water flow/water noise may disturb room occupants (e.g., in hospital wards or other areas where people may be present in the vicinity of the waterways). Yet another issue relates to the fact that only areas of the waterway that are in contact with the hot water supply may be sufficiently cleaned or disinfected, with a result that other areas of the waterway that are only in contact with cold water may not be cleaned adequately.
It would be advantageous to provide an improved valve and/or cleaning method to address one or more of the aforementioned challenges.